While I might very occasionally use dedicated pet product retailers (such as Pets at Home or Jollyes), I buy most of what I need for my cats from supermarkets (e.g. Asda or Morrison's for cat food) or discount stores (e.g. Pet Hut in Poundstretcher, Wilko or B&M for things like cat beds).
I felt sad when a small, local pet shop closed down in Stowmarket but then realised that, apart from once buying a greetings card (with a cat picture on it) in there, I probably hadn't actually ventured into it for over a decade. So I can understand why it's hard for independent pet shops to make money.